Proline

Also known as: L-Proline

INCI: Proline | Function: Anti-aging, Collagen Precursor | Type: Humectant

What Is Proline?

Proline is a unique cyclic amino acid that constitutes approximately 15% of collagen's amino acid composition. It is essential for collagen triple-helix stability and serves as a precursor for hydroxyproline — the amino acid that gives collagen its structural integrity. In skincare, proline supports the skin's natural collagen production and functions as part of the NMF for hydration. Also used in hair care for its conditioning and strengthening properties.

Key Skin Benefits

Pros

Cons

Specifications

PropertyValue
Usage AreasFace, Eye, Body, Hair
Product TypeLeave-On, Rinse-Off
SourceSynthetic / Fermentation
Natural LevelNatural-derived

Safety Ratings

MetricRating
Skin Sensitivity1/5
Comedogenic Rating0/5
EWG Score1/10

Regional Regulatory Limits

RegionLeave-on %Rinse-off %Status
EU (CosIng)No limitNo limitAllowed
US (CIR/FDA)No limitNo limitAllowed
Japan (MHLW)No limitNo limitAllowed
ASEANNo limitNo limitAllowed
China (NMPA)No limitNo limitAllowed

Typical Usage % by Product Type

Product TypeTypical %
Serum0.1 - 1%
Moisturizer0.05 - 0.5%
Hair Treatment0.5 - 2%

References

  1. Shoulders MD, Raines RT — Collagen structure. Annu Rev Biochem (2009). PMID: 19344236
  2. Krane SM — Hydroxyproline and collagen. J Invest Dermatol (2008)
  3. Nimni ME — Collagen biochemistry (1988). CRC Press
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